THE complex heterogeneity of cell populations in the nervous system severely limits the study of many important questions in neurobiology. Improvement of the current techniques of neuronal cell culture will require methods for selective isolation of neurones belonging to specific functional classes. Present methods include a degree of separation of neurones from non-neuronal cells by physical methods1-3 but these differentiate only on the basis of size or density. The separation of classes of tumour cells and lymphocytes has been accomplished by affinity chromatography using lectins or antibodies against surface antigens4-7. In principle neurone purification could be approached in the same way. Among other surface identities, neurones have neurotransmitter receptors which provide one basis for functional classification and potentially provide targets for affinity probes of high specificity. As a model system we chose the chick embryo sympathetic ganglion neurones which are known to possess high numbers of the nicotinic type of acetylcholine (ACh) receptor8. These cells also possess high numbers of receptors for α-bungarotoxin (αBT)9. We report here the successful separation by affinity chromatography of the principal neurones from sympathetic ganglia using αBT as a probe.